The present invention relates generally to machines for tenderizing meat or other material through a cutting or slitting action. More specifically, the invention relates to a knife assembly used in carrying out the cutting or slitting operation.
Meat tenderizing machines have been known for some time. One example of such a tenderizing machine is shown in U.S. Pat. No. 2,605,497 issued Aug. 5, 1952 to Spang. The basic machine components disclosed in Spang are still included in most tenderizers of the present day, although the outward appearances of such machines have been modernized.
The typical tenderizing machine includes a chute passing through the machine, into which a piece of meat may be placed for tenderizing. Disposed along the chute is a pair of intermeshed cylindrical knife rolls, each roll being provided with a plurality of cutting or slitting discs that operate upon the meat. The rolls are located alohg the chute so that meat is passed between the rolls, whereupon a gang cutting operation is performed upon both sides of the meat.
As can be readily appreciated, one important consideration in designing a meat tenderizer is to provide for the relatively convenient cleaning of the knife rolls. The close spacing of the individual blades creates many potential locations for collection of meat particles, with the result that the knife rolls must be carefully cleaned. To facilitate such cleaning, the rolls are typically mounted in a removable unit which may be lifted from the machine. As shown in the Spang patent, the unit is provided with a handle portion, and each knife roll shaft is adapted for quick connection with and disconnection from the machine drive motor. Thus, the entire tenderizing unit may be lifted from the machine and taken to a more convenient location for cleaning.
To ensure that meat particles do not collect along the blades and adversely affect operation between cleanings, each knife roll is accompanied by a comb member disposed adjacent the roll. The comb is provided with a plurality of slots, one slot for each blade on the roll. Rotation of the rolls for tenderizing rotates the knifes through the slots of the comb, thereby stripping any large meat particles from the knife blades.
The typical manner in which a knife roll is assembled is shown in U.S. Pat. No. 2,886,846, issued May 19, 1959 to Meyer. Each knife disc includes a central opening, and is positioned on a shaft for rotation. In order to ensure that the blades remain spaced along the shaft, a spacer disc is positioned between each adjacent pair of blades. After all blades and spacers are located on the shaft, appropriate end fittings are attached to hold the assembly together.
This assembly technique for the knife roll has remained essentially unchanged for some time, notwithstanding the existence of several problems. Because the knife rolls of the pair are positioned in an intermeshing relationship, the spacing between the individual blades of each roll must be substantially uniform to provide proper meshing of the blades. In addition, the spacing must be maintained uniformly along the entire roll to ensure that each blade will pass cleanly through its slot in the corresponding comb. Otherwise, misalignment of one or more blades could cause a blade to contact either another blade on the opposite roll or the comb, possibly resulting in either breaking of one or more blades or jamming of the machine.
In addition, assembly of the knife roll is a tedious task. A typical roll includes approximately 40 blades, which must each be individually stacked, in alternating fashion with spacer discs, onto the roll shaft. Great care must be taken in manufacturing both the individual blades and the spacers, since the approximately 80 elements placed onto each shaft can accumulate tolerances adversely over the length of the shaft, thereby preventing the roll from intermeshing with the opposite roll or comb. The blades and spacers must also be tightly compressed by the end fittings to make certain that the entire roll assembly rotates as a unit, as well as that no meat particles collect between the spacers and knife blades.
As the knife roll is used within the tenderizing machine, the blades will become worn. Such wear is generally most pronounced along the center portion of the roll, along which most of the meat to be tenderized will pass. Further, it is not uncommon for bone chips and other hard particles to be inadvertently passed through the tenderizing machine. Thus, it is not unusual for one or more blades to become broken or bent as the tenderizer is used.
Broken blades can be replaced by disassembling the roll assembly, replacing the blades, and putting the roll assembly back together. However, due to the tedious nature of such a task, as well as the possibility that the reassembled roll may not properly fit with the comb or opposite roll, it is more common for the tenderizer simply to be operated with one or more broken blades. Once a sufficient number of blades has been broken, the entire roll is repaired and/or replaced.
Should blades become bent during tenderizer operations, the machine can no longer be run. The roll then must be repaired or replaced.
In view of the foregoing problems, it can be seen that an improved knife roll assembly is needed that overcomes the disadvantages inherent in assemblies presently in use. Particularly, such an assembly should be simpler and more economical to manufacture, and should be capable of manufacture with more accurate control of blade spacing. Such a roll should also provide for relatively simple replacement of broken, worn or bent blades.